The present invention is related generally to printed circuit boards, and more specifically to expansion slots for printed circuit boards.
Modern personal computers include an increasing number of separate internal peripheral devices and components. Representative peripheral devices include, but are not limited to, internal modems, sound cards, video adapters, graphics accelerators, accelerator boards, and the like. Representative components include, but are not limited to, cache chips, memory chips, and hard drives.
Typically, peripheral components in a computer system are connected to a printed circuit board (PCB) such as a motherboard or the like through a bus. For example, buses such as Peripheral Component Interconnect (PCI), Industry Standard Architecture (ISA), and Extended ISA (EISA) bus slots are used in computer systems for connection of peripherals such as sound and video cards, modems, and the like. The boards inserted into the expansion slots may be called expansion boards, expansion cards, cards, add-ins, add-ons, and the like.
In addition to PCI, ISA, and EISA expansion slots, other expansion slots in PCBs may be used for adding new capabilities to the computer such as adding more memory, graphics capabilities, and support for special devices. In certain instances, add-on devices such as single in-line memory modules (SIMMs), dual in-line memory modules (DIMMs) and other expansion cards in computers having multiple expansion slots must be installed in a correct sequence for proper function of the device and the computer after installation of the device.
In computer systems and expansion slots in which the correct sequence of installation of add-ons is required, current industry standard practice is to rely on the user to read an instruction set, either at the expansion slot or in a separate manual, or to label the expansion slots in the required order of use. Such practice is unreliable, as many users do not know that certain expansion add-ons must be correctly sequenced in multiple slots. Further, many users do not attempt to verify that the proper methods are being used to install add-ons. It is only after the computer does not function properly that many users turn to additional guidance such as a manual or instruction set.
It would be desirable, therefore, to provide expansion slots that must be used in the proper order.
The embodiments of the present invention overcome the problems of the prior art by providing a set of expansion slots in a computer in which the only available slot for placement of an add-on is the proper slot. In one embodiment, such a set of expansion slots includes a mechanical lockout mechanism with a cascading set of components that allows access to only the appropriate slot at any given time. Once the current appropriate expansion slot is filled, the next available correct expansion slot becomes available.
In another embodiment, a lockout apparatus for a plurality of expansion slots including a first and last slot, and intermediate slots, includes a number of lockout mechanisms, one for each of the intermediate expansion slots and the last expansion slot. Each lockout mechanism has a lockout member movable between a first position in which its respective expansion slot is blocked, and a second position in which its respective expansion slot is open. Each of the lockout mechanisms includes a lockout disk rotatable about a central point, the lockout disk having a lockout member fixedly rigidly attached to the lockout disk, the lockout member extending into its respective expansion slot, a lockout opening aligned with the lockout channel when the lockout member is in its first position, and a lockout rod rotatably mounted to the lockout disk. The lockout rod extends into the lockout channel and lockout opening of the adjacent expansion slot when the lockout member is in its first position, and movable out of the lockout opening of the adjacent expansion slot when the lockout member moves to its second position.
In yet another embodiment, each of the lockout mechanisms includes a body having a first end and a second end, a displacement tab extending from the first end, and an add-on card opening positioned between the first end and the second end.
In still yet another embodiment, each of the lockout mechanisms includes a power supply, a switch with a contact disposed in a first expansion slot, and a lockout solenoid in a second expansion slot, the switch connected between the power supply and the lockout solenoid, wherein actuation of the switch actuates the lockout solenoid to retract a lockout member from the second expansion slot.
A method embodiment of the present invention includes blocking access to all but the first of the plurality of expansion slots, and opening access to the next of the plurality of expansion slots upon installation of an add-on card into the first of the expansion slots.